Atmospheric heavy metal deposition in agro-ecosystems in China

Abstract

Atmospheric deposition has become one of the main sources of heavy metals in crops in developed and industrial zones in China for the past several years. However, lack of data of the agro-ecosystems on the vast areas of China makes it difficult to assess the impacts of air pollution on the heavy metal accumulation in crops. In this study, with deposit samples from 67 sites located at different agro-ecosystems (typical, factory nearby, town nearby, roadside, and remote) of four natural regions [Huanghuai (HH), Southeast (SE), Southwest (SW) and upper-mid Yangzi River (Up-mid YR)], atmospheric heavy metal deposition in agro-ecosystems on a large scale in China was studied. The results showed that during the growing season, the deposition fluxes of Cr, Ni, As, Cd, and Pb in typical agro-ecosystems were 0.60-36.86, 0.65-25.37, 0.05-8.88, 0.12-5.81, and 0.43-35.63 μg m day, respectively, which varied greatly between the four different regions. The average deposition fluxes of Cr, Ni, Cd, and Pb in the HH region, as well as the fluxes of As in the SW region, were significantly higher than those in the SE region. Heavy metal deposition rates among agro-ecosystems were very similar, except for the sites around cement factory in flat HH region. In mountainous SW region, however, deposition rates varied widely with sites nearby towns relatively higher and remote regions much lower. Higher correlation coefficients were observed between Cr, As, Pb, and Ni deposition rates, suggesting that they had similar sources. Samples from the SW and SE regions exhibited higher Pb/Pb and Pb/Pb ratios than those from the HH and Up-mid YR regions. Airborne Pb in SW agro-ecosystems were mainly derived from vehicle exhaust and local smelting, whereas that in the HH region from burning of northern Chinese coal.

Flux and source-sink relationship of heavy metals and arsenic in the Bohai Sea, China

“…To prove the representativeness, we conducted extensive comparisons between measured fluxes in this study and fluxes measured in other areas of China. Results showed that the atmospheric deposition rates around the BS and NYS were lower than those measured in the Pearl River Delta (Wong et al, 2003), North China (Pan and Wang, 2015), Beijing (Guo et al, 2017), and agro-ecosystems in China (Zhang et al, 2017b). However, these deposition rates were comparable with the deposition levels monitored in the Jiaozhou Bay and in several Chinese terrestrial ecosystems (Xing et al, 2017;Zhu et al, 2016).…”

Cadmium pollution from phosphate fertilizers in arable soils and crops: an overview

“…Several studies have found that 50%-70% less cadmium accumulates in maize and some vegetables (amaranth, cabbage, and lettuce), most likely due to the supply of calcium from lime and its absorption competition with cadmium [80][81][82] . However, this lime addition might not diminish cadmium uptake in alkaline soils, under deeper rooting or due to the antagonism with Mongolian Plateau, Northwest 1.04 [63] Beijing, North China 4.75 [64] Tianjin, North China 5.30 [64] Hebei, North China 5.57 [64] Henan, North China 4.93 [65] Shanxi, North China 2.04 [65] Fujian, Southeast 0.91 [65] Lianyuan, Southeast 17.00 [66] Shenzhen, Southeast 7.42 [66] Guizhou, Southwest 2.01 [65] Jiaozhou Bay, Central Yellow Sea 1.30 [67] Daya Bay, South China Sea 1.60 [68] East China Sea 1.78 [69] Southern Yellow Sea 1.80 [69] Ca + in the soil solution [26] . When calculating the cadmium outputs from the soil, crop uptake and leaching must be considered (Table 5) [15,44,61] .…”

Occurrence, Risk, and Source of Heavy Metals in Lake Water Columns and Sediment Cores in Jianghan Plain, Central China

“…Ni is considered an indicator of fuel combustion [ 39 , 40 ] and used in industrial production as a raw material or catalyst [ 46 , 50 ]; thus, Ni and TN, TP, and NH 4 + -N lack the same source, although they have significant positive relationships. Pb is not only in the tail gas of oil combustion (entering the lake via atmospheric sedimentation) [ 51 ], but also an important element in automobile manufacturing (such as additives for airbag detonators) [ 52 ]; thus, automobile exhaust and industry are the major sources of Pb. Mn is commonly used as a reducing agent and catalyst in the production of materials such as alloys and magnetic components [ 53 ].…”

“…For example, Pb is not only the waste from automobile manufacturing and fuel [ 51 , 52 ], but also an important component of feed additives together with Zn and Cu [ 49 ]. Apart from the production of fertilizer and pesticides (sodium arsenate and calcium arsenate) [ 38 ], As can also be used together with Co, Ni, and Mn in chemical industry and metal smelting as a combustion promoter or catalyst [ 39 , 51 ]. Cd and Zn are indispensable raw materials for brakes, tires, and lubricants [ 54 ].…”